1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/arch/alpha/kernel/process.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 */
7
8 /*
9 * This file handles the architecture-dependent parts of process handling.
10 */
11
12 #include <linux/errno.h>
13 #include <linux/module.h>
14 #include <linux/sched.h>
15 #include <linux/sched/debug.h>
16 #include <linux/sched/task.h>
17 #include <linux/sched/task_stack.h>
18 #include <linux/kernel.h>
19 #include <linux/mm.h>
20 #include <linux/smp.h>
21 #include <linux/stddef.h>
22 #include <linux/unistd.h>
23 #include <linux/ptrace.h>
24 #include <linux/user.h>
25 #include <linux/time.h>
26 #include <linux/major.h>
27 #include <linux/stat.h>
28 #include <linux/vt.h>
29 #include <linux/mman.h>
30 #include <linux/elfcore.h>
31 #include <linux/reboot.h>
32 #include <linux/tty.h>
33 #include <linux/console.h>
34 #include <linux/slab.h>
35 #include <linux/rcupdate.h>
36
37 #include <asm/reg.h>
38 #include <linux/uaccess.h>
39 #include <asm/io.h>
40 #include <asm/hwrpb.h>
41 #include <asm/fpu.h>
42
43 #include "proto.h"
44 #include "pci_impl.h"
45
46 /*
47 * Power off function, if any
48 */
49 void (*pm_power_off)(void) = machine_power_off;
50 EXPORT_SYMBOL(pm_power_off);
51
52 #ifdef CONFIG_ALPHA_WTINT
53 /*
54 * Sleep the CPU.
55 * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts.
56 */
arch_cpu_idle(void)57 void arch_cpu_idle(void)
58 {
59 wtint(0);
60 }
61
arch_cpu_idle_dead(void)62 void arch_cpu_idle_dead(void)
63 {
64 wtint(INT_MAX);
65 }
66 #endif /* ALPHA_WTINT */
67
68 struct halt_info {
69 int mode;
70 char *restart_cmd;
71 };
72
73 static void
common_shutdown_1(void * generic_ptr)74 common_shutdown_1(void *generic_ptr)
75 {
76 struct halt_info *how = generic_ptr;
77 struct percpu_struct *cpup;
78 unsigned long *pflags, flags;
79 int cpuid = smp_processor_id();
80
81 /* No point in taking interrupts anymore. */
82 local_irq_disable();
83
84 cpup = (struct percpu_struct *)
85 ((unsigned long)hwrpb + hwrpb->processor_offset
86 + hwrpb->processor_size * cpuid);
87 pflags = &cpup->flags;
88 flags = *pflags;
89
90 /* Clear reason to "default"; clear "bootstrap in progress". */
91 flags &= ~0x00ff0001UL;
92
93 #ifdef CONFIG_SMP
94 /* Secondaries halt here. */
95 if (cpuid != boot_cpuid) {
96 flags |= 0x00040000UL; /* "remain halted" */
97 *pflags = flags;
98 set_cpu_present(cpuid, false);
99 set_cpu_possible(cpuid, false);
100 halt();
101 }
102 #endif
103
104 if (how->mode == LINUX_REBOOT_CMD_RESTART) {
105 if (!how->restart_cmd) {
106 flags |= 0x00020000UL; /* "cold bootstrap" */
107 } else {
108 /* For SRM, we could probably set environment
109 variables to get this to work. We'd have to
110 delay this until after srm_paging_stop unless
111 we ever got srm_fixup working.
112
113 At the moment, SRM will use the last boot device,
114 but the file and flags will be the defaults, when
115 doing a "warm" bootstrap. */
116 flags |= 0x00030000UL; /* "warm bootstrap" */
117 }
118 } else {
119 flags |= 0x00040000UL; /* "remain halted" */
120 }
121 *pflags = flags;
122
123 #ifdef CONFIG_SMP
124 /* Wait for the secondaries to halt. */
125 set_cpu_present(boot_cpuid, false);
126 set_cpu_possible(boot_cpuid, false);
127 while (!cpumask_empty(cpu_present_mask))
128 barrier();
129 #endif
130
131 /* If booted from SRM, reset some of the original environment. */
132 if (alpha_using_srm) {
133 #ifdef CONFIG_DUMMY_CONSOLE
134 /* If we've gotten here after SysRq-b, leave interrupt
135 context before taking over the console. */
136 if (in_hardirq())
137 irq_exit();
138 /* This has the effect of resetting the VGA video origin. */
139 console_lock();
140 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
141 console_unlock();
142 #endif
143 pci_restore_srm_config();
144 set_hae(srm_hae);
145 }
146
147 if (alpha_mv.kill_arch)
148 alpha_mv.kill_arch(how->mode);
149
150 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
151 /* Unfortunately, since MILO doesn't currently understand
152 the hwrpb bits above, we can't reliably halt the
153 processor and keep it halted. So just loop. */
154 return;
155 }
156
157 if (alpha_using_srm)
158 srm_paging_stop();
159
160 halt();
161 }
162
163 static void
common_shutdown(int mode,char * restart_cmd)164 common_shutdown(int mode, char *restart_cmd)
165 {
166 struct halt_info args;
167 args.mode = mode;
168 args.restart_cmd = restart_cmd;
169 on_each_cpu(common_shutdown_1, &args, 0);
170 }
171
172 void
machine_restart(char * restart_cmd)173 machine_restart(char *restart_cmd)
174 {
175 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
176 }
177
178
179 void
machine_halt(void)180 machine_halt(void)
181 {
182 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
183 }
184
185
186 void
machine_power_off(void)187 machine_power_off(void)
188 {
189 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
190 }
191
192
193 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever
194 saved in the context it's used. */
195
196 void
show_regs(struct pt_regs * regs)197 show_regs(struct pt_regs *regs)
198 {
199 show_regs_print_info(KERN_DEFAULT);
200 dik_show_regs(regs, NULL);
201 }
202
203 /*
204 * Re-start a thread when doing execve()
205 */
206 void
start_thread(struct pt_regs * regs,unsigned long pc,unsigned long sp)207 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
208 {
209 regs->pc = pc;
210 regs->ps = 8;
211 wrusp(sp);
212 }
213 EXPORT_SYMBOL(start_thread);
214
215 void
flush_thread(void)216 flush_thread(void)
217 {
218 /* Arrange for each exec'ed process to start off with a clean slate
219 with respect to the FPU. This is all exceptions disabled. */
220 current_thread_info()->ieee_state = 0;
221 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
222
223 /* Clean slate for TLS. */
224 current_thread_info()->pcb.unique = 0;
225 }
226
227 /*
228 * Copy architecture-specific thread state
229 */
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)230 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
231 {
232 unsigned long clone_flags = args->flags;
233 unsigned long usp = args->stack;
234 unsigned long tls = args->tls;
235 extern void ret_from_fork(void);
236 extern void ret_from_kernel_thread(void);
237
238 struct thread_info *childti = task_thread_info(p);
239 struct pt_regs *childregs = task_pt_regs(p);
240 struct pt_regs *regs = current_pt_regs();
241 struct switch_stack *childstack, *stack;
242
243 childstack = ((struct switch_stack *) childregs) - 1;
244 childti->pcb.ksp = (unsigned long) childstack;
245 childti->pcb.flags = 1; /* set FEN, clear everything else */
246 childti->status |= TS_SAVED_FP | TS_RESTORE_FP;
247
248 if (unlikely(args->fn)) {
249 /* kernel thread */
250 memset(childstack, 0,
251 sizeof(struct switch_stack) + sizeof(struct pt_regs));
252 childstack->r26 = (unsigned long) ret_from_kernel_thread;
253 childstack->r9 = (unsigned long) args->fn;
254 childstack->r10 = (unsigned long) args->fn_arg;
255 childregs->hae = alpha_mv.hae_cache;
256 memset(childti->fp, '\0', sizeof(childti->fp));
257 childti->pcb.usp = 0;
258 return 0;
259 }
260 /* Note: if CLONE_SETTLS is not set, then we must inherit the
261 value from the parent, which will have been set by the block
262 copy in dup_task_struct. This is non-intuitive, but is
263 required for proper operation in the case of a threaded
264 application calling fork. */
265 if (clone_flags & CLONE_SETTLS)
266 childti->pcb.unique = tls;
267 else
268 regs->r20 = 0; /* OSF/1 has some strange fork() semantics. */
269 childti->pcb.usp = usp ?: rdusp();
270 *childregs = *regs;
271 childregs->r0 = 0;
272 childregs->r19 = 0;
273 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
274 stack = ((struct switch_stack *) regs) - 1;
275 *childstack = *stack;
276 childstack->r26 = (unsigned long) ret_from_fork;
277 return 0;
278 }
279
280 /*
281 * Fill in the user structure for a ELF core dump.
282 */
283 void
dump_elf_thread(elf_greg_t * dest,struct pt_regs * pt,struct thread_info * ti)284 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
285 {
286 /* switch stack follows right below pt_regs: */
287 struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
288
289 dest[ 0] = pt->r0;
290 dest[ 1] = pt->r1;
291 dest[ 2] = pt->r2;
292 dest[ 3] = pt->r3;
293 dest[ 4] = pt->r4;
294 dest[ 5] = pt->r5;
295 dest[ 6] = pt->r6;
296 dest[ 7] = pt->r7;
297 dest[ 8] = pt->r8;
298 dest[ 9] = sw->r9;
299 dest[10] = sw->r10;
300 dest[11] = sw->r11;
301 dest[12] = sw->r12;
302 dest[13] = sw->r13;
303 dest[14] = sw->r14;
304 dest[15] = sw->r15;
305 dest[16] = pt->r16;
306 dest[17] = pt->r17;
307 dest[18] = pt->r18;
308 dest[19] = pt->r19;
309 dest[20] = pt->r20;
310 dest[21] = pt->r21;
311 dest[22] = pt->r22;
312 dest[23] = pt->r23;
313 dest[24] = pt->r24;
314 dest[25] = pt->r25;
315 dest[26] = pt->r26;
316 dest[27] = pt->r27;
317 dest[28] = pt->r28;
318 dest[29] = pt->gp;
319 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
320 dest[31] = pt->pc;
321
322 /* Once upon a time this was the PS value. Which is stupid
323 since that is always 8 for usermode. Usurped for the more
324 useful value of the thread's UNIQUE field. */
325 dest[32] = ti->pcb.unique;
326 }
327 EXPORT_SYMBOL(dump_elf_thread);
328
329 int
dump_elf_task(elf_greg_t * dest,struct task_struct * task)330 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
331 {
332 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
333 return 1;
334 }
335 EXPORT_SYMBOL(dump_elf_task);
336
elf_core_copy_task_fpregs(struct task_struct * t,elf_fpregset_t * fpu)337 int elf_core_copy_task_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
338 {
339 memcpy(fpu, task_thread_info(t)->fp, 32 * 8);
340 return 1;
341 }
342
343 /*
344 * Return saved PC of a blocked thread. This assumes the frame
345 * pointer is the 6th saved long on the kernel stack and that the
346 * saved return address is the first long in the frame. This all
347 * holds provided the thread blocked through a call to schedule() ($15
348 * is the frame pointer in schedule() and $15 is saved at offset 48 by
349 * entry.S:do_switch_stack).
350 *
351 * Under heavy swap load I've seen this lose in an ugly way. So do
352 * some extra sanity checking on the ranges we expect these pointers
353 * to be in so that we can fail gracefully. This is just for ps after
354 * all. -- r~
355 */
356
357 static unsigned long
thread_saved_pc(struct task_struct * t)358 thread_saved_pc(struct task_struct *t)
359 {
360 unsigned long base = (unsigned long)task_stack_page(t);
361 unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
362
363 if (sp > base && sp+6*8 < base + 16*1024) {
364 fp = ((unsigned long*)sp)[6];
365 if (fp > sp && fp < base + 16*1024)
366 return *(unsigned long *)fp;
367 }
368
369 return 0;
370 }
371
372 unsigned long
__get_wchan(struct task_struct * p)373 __get_wchan(struct task_struct *p)
374 {
375 unsigned long schedule_frame;
376 unsigned long pc;
377
378 /*
379 * This one depends on the frame size of schedule(). Do a
380 * "disass schedule" in gdb to find the frame size. Also, the
381 * code assumes that sleep_on() follows immediately after
382 * interruptible_sleep_on() and that add_timer() follows
383 * immediately after interruptible_sleep(). Ugly, isn't it?
384 * Maybe adding a wchan field to task_struct would be better,
385 * after all...
386 */
387
388 pc = thread_saved_pc(p);
389 if (in_sched_functions(pc)) {
390 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
391 return ((unsigned long *)schedule_frame)[12];
392 }
393 return pc;
394 }
395